Division of Neurology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Department of Medical Genetics and Ophthalmology & Visual Sciences, Faculty of Medicine and Dentistry, Royal Alexandra Hospital, Edmonton, Alberta, Canada.
Hippocampus. 2024 Nov;34(11):625-632. doi: 10.1002/hipo.23637. Epub 2024 Sep 11.
Hippocampal subfields perform specific roles in normal cognitive functioning and have distinct vulnerabilities in neurological disorders. However, measurement of subfields with MRI is technically difficult in the head and tail of the hippocampus. Recent studies have utilized curved multiplanar reconstruction (CMPR) to improve subfield visualization in the head and tail, but this method has not yet been applied to histological data.
We utilized BigBrain data, an open-source database of serially sectioned histological data for our analyses. The left hippocampus was segmented according to histological criteria by two raters in order to evaluate intra- and inter-rater reliability of histology-based segmentation throughout the long axis. Segmentation according to our previous protocol for the hippocampal body was then compared to these histological measurements to evaluate for histological validity. Agreement between segmentations was evaluated using Dice similarity coefficients (DSCs).
Intra-rater reliability (DSCs) of histological segmentation was excellent for all subfields: CA1 (0.8599), CA2 (0.7586), CA3/CA4/DG (0.8907), SLM (0.9123), subiculum (0.8149). Similarly, inter-rater reliability analysis demonstrated excellent agreement (DSCs) for all subfield locations: CA1 (0.8203), CA2 (0.7253), CA3/CA4/DG (0.8439), SLM (0.8700), subiculum (0.7794). Finally, histological accuracy (DSCs) for our previous protocol was excellent for all subfields: CA1 (0.8821), CA2 (0.8810), CA3/CA4/DG (0.9802), SLM (0.9879), subiculum (0.8774). When subfields in the hippocampus head, body, and tail were analyzed independently, DSCs also showed excellent agreement.
CMPR allows reliable subfield segmentation based on histological criteria throughout the hippocampal head, body, and tail. Our previous protocol for the hippocampal body can be applied to provide histologically valid subfield measurements throughout the entire hippocampal long axis.
海马亚区在正常认知功能中发挥特定作用，在神经退行性疾病中具有明显的脆弱性。然而，头部和尾部的海马亚区的 MRI 测量在技术上具有挑战性。最近的研究已经利用了曲面多平面重建（CMPR）来改善头部和尾部的亚区可视化，但这种方法尚未应用于组织学数据。
我们利用了 BigBrain 数据，这是一个用于分析的连续切片组织学数据的开源数据库。两名评分者根据组织学标准对左侧海马进行分割，以评估长轴上基于组织学分割的内部和外部评分者之间的可靠性。然后，将根据我们之前的海马体协议进行的分割与这些组织学测量进行比较，以评估组织学的有效性。使用 Dice 相似系数（DSC）评估分割之间的一致性。
所有亚区的组织学分割的内部评分者可靠性（DSC）均非常好：CA1（0.8599）、CA2（0.7586）、CA3/CA4/DG（0.8907）、SLM（0.9123）、下托（0.8149）。同样，内部评分者可靠性分析显示所有亚区位置的一致性（DSC）非常好：CA1（0.8203）、CA2（0.7253）、CA3/CA4/DG（0.8439）、SLM（0.8700）、下托（0.7794）。最后，我们之前的协议的组织学准确性（DSC）对于所有亚区都非常好：CA1（0.8821）、CA2（0.8810）、CA3/CA4/DG（0.9802）、SLM（0.9879）、下托（0.8774）。当单独分析海马头部、体部和尾部的亚区时，DSC 也显示出非常好的一致性。
CMPR 允许基于组织学标准在整个海马头部、体部和尾部进行可靠的亚区分割。我们之前的海马体协议可以应用于整个海马长轴提供具有组织学有效性的亚区测量。
